Solve the following expression and give your answer as a fraction. $ -\dfrac{21}{25} \times 0.36 = {?} $
First get all of the numbers as simplified fractions. $ 0.36 = \dfrac{3.6}{10} = \dfrac{9}{25} $ Now we have: $ -\dfrac{21}{25} \times \dfrac{9}{25} = {?} $ $ \phantom{ -\dfrac{21}{25} \times \dfrac{9}{25} } = \dfrac{-21 \times 9 } {25 \times 25 } $ $ \phantom{ -\dfrac{21}{25} \times \dfrac{9}{25} } = -\dfrac{189}{625} $